Acrylonitrile spinning solutions and method of producing filaments therefrom



United States Patent A JRYLQNHTRELE SPENNENG SQLUHQNS AND METHQD @llllfiiBUfilNG FHILAMENTS TEERE FRQM Harry W. (louver, .lln, and Willis(1. Wooten, Jr., Kingsport, Tenn, assignors to Eastman Kodak Company,Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Dec. 18,1961, Ser. No. 160,297

21 Claims. (Cl. 264-206) This invention relates to a novel solventcomposition and to spinning solutions prepared therefrom. Moreparticularly, this invention relates to spinning solutions for theproduction of filaments of acrylonitrile polymers.

Fibers, filaments and the like prepared from polymers of acrylonitrile,particularly those polymers having a high content of acrylonitrile(usually 65 percent and higher), have proved highly satisfactory for usein the manufacture of a diversity of fabrics and the like. However, thepolymers of acrylonitrile containing in excess of about 65 percent ofacrylonitrile are generally incapable of solution in the ordinarysolvents commonly employed for preparing conventional spinningsolutions.

A number of solvent mediums have been proposed heretofore for use inpreparing solutions of the acrylonitrile polymers that are difiieultlysoluble. For example, it has been proposed to employN,N-dimethylformamide, N,N'-dimethylacetamide, nitromethane, andmixtures thereof to obtain spinnable solutions of the polymers ofacrylonitrile having an acrylonitrile content of 65 percent by weightand higher.

These solvents are expensive and hence have not enjoyed widespread usein the art. Also, these solvent mediums have relatively low volatilitynecessitating high temperatures for solvent removal when dry-spinningprocesses are employed. Further, these solvent mediums have relativelylow miscibility with water and hence present a problem of rapid solventremoval in aqueous coagulating baths.

An object of this invention is an improved solvent composition for usein preparing spinning solutions of acrylonitrile polymers, particularlythe acrylonitrile polymers containing at least about 65 percent byweight of acrylonitrile, and particularly those acrylonitrile polymersthat are difiicultly soluble.

Another object of this invention is a-spinning solution for thepreparation of filaments and fibers of acrylonitrile polymers containing65 percent by Weight of acrylonitrile and higher.

A further object of this invention is an improved process for thefabrication of filaments, fiberaand the like of acrylonitrile polymerscontaining at least about 65 percent by Weight of acrylonitrile.

Other objects of this invention will, in part, be obvious and will, inpart, appear hereinafter.

For a complete understanding of the nature and the objects of thisinvention, reference is made to the following detailed description.

in accordance with this invention there is provided a novel solventcomposition for use in preparing spinning solutions of acrylonitrilepolymers containing at least about 65 percent by weight ofacrylonitrile. The solvent composition of this invention is comprised offrom about 98 percent to 60 percent by weight of acetonitrile and fromabout 2 percent to 40 percent by weight of a specific inorganic salt tobe detailed hereinafter.

Further, and in accordance with this invention, there is provided anovel spinning solution which is comprised of the novel solventcomposition of this invention and an acrylonitrile polymer containing atleast about 65 percent by weight of acrylonitrile. The spinningsolutions 3,194,362 Patented July 13, 1965 of this invention willcomprise, by weight, from about 10 percent to 30 percent of theacrylonitrile polymer and from about 90 percent to 70 percent of thesolvent composition.

It has been determined that a solvent composition comprised of, byweight, from about 2 percent to 10 percent of the inorganic salt andfrom about 98 percent to 90 percent of acetonitrile is highlysatisfactory for preparing spinning solutions of those acrylonitrilepolymers containing, by weight, from about 65 percent to 70 percent ofacrylonitrile. For those acrylonitrile polymers containing about 90percent and more of acrylonitrile, it is preferred to employ a solventcomposition comprised of, by weight, from about 20 percent to 40 percentof the inorganic salt and from about percent to 60 percent ofacetonitrile.

Also, and in accordance with this invention, it has been determined thatup to about 15 percent by weight of water based on the weight of theacetonitrile can be incorporated into the novel solvent composition ofthis invention to improve and hasten the dissolution of the inorganicsalt therein.

The inorganic salts employed in preparing the novel solvent compositionof this invention are those that are substantially soluble inacetonitrile and will have the formula C A wherein C is a cationselected from the group consisting of K+, Pb NHJ, Cd Al+++,- Na+, c 3 }Ai+ 1 1+++ Sn++++, Zn++, Ag Ni++, Co++, and Mn++; wherein A is an anionselected from the group consisting of 1*, Br, N0 1 S04 and SCN; andwherein x and y are integers such that the total charge on the cationportion of the molecule or salt equals the total charge on the anionportion of the molecule or salt.

Specificexamples of inorganic salts that can be employed in preparingthe novel compositions of this invention include sodium iodide,potassium thiocyanate, sodium thiocyanate, lithium bromide, calciumthiocyanate, silver nitrate, ammonium thiocyanate, and zinc bromide.Mixtures of two or more of the above salts can be employed if desired.

The solvent composition of this invention is particularly useful inproviding solutions comprising polymers of acrylonitrile in which theacrylonitrile content is equal to about 65 percent by weight and higher,and particularly polymers of this type that are diflicultly soluble inthe more common types of spinning solvents. However, the solventcomposition can be employed satisfactorily to prepare solutions ofacrylonitrile polymers wherein the acrylonitrile content issubstantially less than about 65 percent by weight, if desired.

The solvent composition of this invention can be prepared convenientlyby dissolving the inorganic salt in acetonitrile in an amount sutficientto provide a solvent composition of desired proportions of the inorganicsalt and the acetonitrile. It is preferred to use the inorganic salt infinely divided form in order to hasten dissolution thereof in theacetonitrile. The dissolution of the inorganic salt in acetonitrile canbe readily and easily accomplished at room temperature (23 0.); however,heating to a temperature above room temperature, usually not in excessof about 80 C., with stirring, can be employed to hasten dissolution ofthe salt. .As above set forth a small amount of Water can be added tothe solvent composition to improve the solubility characteristics of theinorganic salt in the acetonitrile.

The acrylonitrile polymer is subsequently added to the solventcomposition of this invention in an amount sufficient to provide aspinning solution comprising from about 10 percent to 30 percent byWeight of the acrylonitrile polymer and from about 99 percent to 70percent by Weight of the solvent composition. The acrylonitrile polymerisadded preferably in finely divided form with rapid stirring followedbyheating to complete'the dissolution of the polymer in the solventcomposition.

The acrylonitrile polymers that can be employed in the 'practice of thisinvention. arepolyacrylonitrile, copolymers of acrylonitrile,-includingbinary and ternary poly- .mers containingat least about 65 percent byweight of acrylonitrile in the polymer molecule. The acrylonitrilepolymers of special interest'for use in thisinvention are 'those thatare negligiblysoluble in acetonitrile alone.

Examples of acrylonitrilepolymerswhich are particularly adapted for usein carrying out this'invention include those polymers comprised of fromabout 2 percent to 35 percent by weight of methyl acrylate and fromabout 98 percent to 65 percent of acrylonitrile, a specific examplebeing that polymer having excellent dyeing properties comprised of, byweight, about 10 percent of methyl acrylate and90 percent ofacrylonitrile; a polymencomprised of 5 percent by weight ofvinylacetate, 20 percent by weight of vinylidene chloride, and 75percent by weight of acrylonitrile; a polymer comprised of about 7%percent by weight of methyl acrylate, about 12 /2 percent by weight ofvinylidene chloride and about 80- percent by weight of acrylonitrile;and a polymer comprised-of about percent by weight of methylacr'ylate,-about 10 percent by weight of methyl methacrylate'and about80 percent by weight-of acrylonitrile.

The novel solvent composition -of this-invention permits the use ofrelatively moderate spinning temperatures of the order from-about 70 to80 C. When dry-spin- -'ning-tecl1niques are employed informing filamentsfrom the spinning solution of this invention, solvent removal from theformed filaments can be accomplished by use of hot air maintained at atemperature of from about 140 C. to 200 C. =When wet-spinning-methodsare employed 1 to form filaments, solvent removal from the formedfilaments can be accomplished by extrusion ofthe spinning solution intoan aqueous coagulating bath maintained at atemperature of from about 60C. to 80 C., with a 7 temperature of about 70 C. being preferred. Aftersol- '-vent removaL-the'thus prepared or extruded filaments aresubsequently stretched or drafted to-about 300'percent to 600 percent-ofits original lengththereby providing filaments satisfactory for use inthe manufacture of textiles.

The following examples are-illustrative of this invention. All parts-areby-weight unless otherwise indicated.

Example I About 10 partsof a 90 percent by weight acrylonitrile- 10percent by-Weight methyl acrylate polymer having a molecularweightof'about 40,000 is dissolved in about 55 parts of a solventcomposition prepared by dissolving about 10parts-of sodium thiocyanatein about 45 parts of acetonitrile. The solution thus prepared isextruded through a'small'orifice into a Water bath. The filament thatis-formed by this extrusion is passed over a hot, roll maintained-at atemperature of about 150 where it is 'dried. The filament is'subsequently drafted to about 300 a percent of its original length. Theresulting fiber is strong,

tough andhas a high softening temperature.

Example II A solvent composition is prepared by dissolving about 10parts of silver nitrate in-about- 40 parts of acetonitrile.

Three parts of an-acrylonitrile polymer comprised of, by

weight, about 92.5 percent of acrylonitrile and about 7.5

percent of methyl acrylate is admixed with about 20 parts of the solventcomposition to provide a spinningsolution.

The spinning solution is tumbled in a container for about 30 minutes.During the tumbling the spinning solution is maintained at a temperatureof about 50 C. On cooling to room temperature (about 23 C.) a viscousspinning solution is-obtained that can be formed into strong,

4 Example III A viscous spinning solution is prepared in substantiallythe same manner as in Example II with the exception that the solventcomposition employed is prepared by dissolving about 10 parts ofammonium thiocyanate in a mixture of about 36 parts of 'acetonitrile andabout 4 parts of water. Filaments spun from this spinning solution arestrong and soften only at relatively high temperatures.

Example IV A viscous spinning solution is prepared in substantially thesame manner as in Example II with the exception that the solventcomposition employed is prepared by dissolving about 10 parts of zincbromide in a mixture of about 4 parts of water and 36 parts ofacetonitrile. Fibers spun from this spinning solution are strong, tough,and have relatively high softening temperatures.

high-temperature softening fibers in accordance with they method ofExample I.

In addition to fibers and filaments, the spinning solutions of thisinvention can be employed in the preparation of other shaped articles ofacrylonitrile polymers wherein the acrylonitrile content is in excess ofabout percent by weight. Examples of such shaped articles include film,sheets, casings, tubings, rods, and the like. These members can beformed by conventional methods well known in the art.

It is to be understood'that the above description and examples areillustrative of this invention and not in limitation thereof.

We claim:

.1. A spinning solution consisting essentially of, by weight, (I) fromabout 10% to 30% of a polymer selected from the group consisting ofpolyacrylonitrile and a copolymer of acrylonitrile and at least oneother substance having ethylenic unsaturation, said copolymer containingat least about 65 by Weight of acrylonitrile and "(11) from about 90% toof a solvent composition consisting essentially of, by weight, (a) fromabout 98% to 60% of acetonitrile and (b) from about 2% to 40% of anacetonitrile soluble inorganic salt having the formula C A wherein C isa cation selected from the group consisting of. K+, Pb++, NHJ, .Cd'Al+++, Na Ba++,

0 1+++ Li-b Zn++, Ag Ni++, Co and Mn wherein A is an i anion selectedfrom the group consisting of I, Br, N0 3 SOf and SCN; and wherein x andy are integers such that the total charge'on the cation portion of themolecule equals the total chargeon the anion portion of the molecule.

2. The spinning solution of claim 1 wherein the (II) (b) inorganic saltis sodium iodide.

3. The spinning solution of claim 1 wherein the (II) (b) salt ispotassium thiocyan'ate.

4. The spinning solution of claim 1 wherein the (II) (b) I salt issodium thiocyanate.

of acrylonitrile the steps which comprise preparing a spinning solutionconsisting essentially of, by weight, (I) from about 10% to30% of apolymer selected from the group consisting of polyacrylonitrile and acopolymer of acrylonitrile and at least one other substance havingethylenic unsaturation, said copolymer containing at least about 65 byweight of acrylonitrile and (II) from about to 70% of a solventcomposition consisting essentially of, by

' Weight, (a) from about 98 to 60% of acetonitrile and (b) from about 2%to 40% of an acetonitrile soluble inorganic salt having the formula C Awherein C is a cation selected from the group consisting of K Pb++, NHJ,1+++ t 3 1 1+++ t Co++, and Mn wherein A is an anion selected from thegroup consisting of 1-, Br, N6 1 S05, and SCN"; and wherein x and y areintegers such that the total charge on the cation portion of themolecule equals the total charge on the anion portion of the molecule,forming the solution into the form of filaments, removing from theformed fila ments substantially all the solvent composition presenttherein, and drafting the resulting filaments whereby there are providedfilaments suitable for use in the manufacture of textiles.

11. The method of claim 1% wherein the filaments are drafted to fromabout 3% percent to 600 percent of their originally formed length.

12. The method of claim wherein the filaments are formed by extrudingthe spinning solution into an atmosphere of air maintained at atemperature of from about 140 C. to 200 C. to remove therefromsubstantially all solvent.

13. The method of claim 18 wherein the filaments are formed by extrudingthe spinning solution into an aqueous coagulating bath maintained at atemperature of from about 60 C. to 80 C.

14. The method of claim it) wherein the (II) (b) in organic salt issodium iodide.

- 15. The method of claim 19 wherein the (II) (b) inorganic salt ispotassium thiocyanate.

16. The method of claim 10 wherein the (II) (b) inorganic salt is sodiumthiocyanate.

17. The method of claim 10 wherein the (II) (b) inorganic salt iscalcium thiocyanate.

18. The method of claim 10 wherein the (II) (b) inorganic salt isammonium thiocyanate.

19. The method of claim 10 wherein the (II) (b) inorganic salt islithium bromide.

Ztl. The method of claim 10 wherein the (II) (b) inorganic salt issilver nitrate.

21. The method of claim 10 wherein the (II) (b) inorganic salt is zincbromide.

References Cited by the Examiner UNITED STATES PATENTS 2,601,252 6/52Brunson "18-54 2,648,648 8/53 Stanton (it al. 260--29.6 -761,754 9/56Jones et al 1854 2,776,945 1/57 Rahl et a1 1s 54 LEON J. BERCOVITZ,Primary Examiner.

10. IN THE METHOD OF PRODUCING FILAMENTS FROM ACRYLONITRILE POLYMERSCONTAINING AT LEAST ABOUT 65% BY WEIGHT OF ACRYLONITRILE THE STEPS WHICHCOMPRISE PREPARING A SPINNING SOLUTION CONSISTING ESSENTIALLY OF, BYWEIGHT, (I) FROM ABOUT 10% TO 30% OF A POLYMER SELECTED FROM THE GROUPCONISITING OF POLYACRYLONITRILE AND A COPOLYMER OF ACRYLONITRILE AND ATLEAST ONE OTHER SUBSTANCE HAVING ETHYLENIC UNSATURATION, SAID COPOLYMERCONTAINING AT LEAST ABOUT 65% BY WEIGHT OF ACRYLONITRILE AND (II) FROMABOUT 90% TO 70% OF A SOLVENT COMPOSITION CONSISTING ESSENTIALLY OF, BYWEIGHT, (A) FROM ABOUT 98% TO 60% OF ACETONITRILE AND (B) FROM ABOUT 2%TO 40% OF AN ACETONITRILE SOLUBLE INORGANIC SALT HAVING THE FORMULA CXAYWHEREIN C IS A CATION SELECTED FROM THE GROUP CONSISTING OF K+,PB++,NH4+, CD++, A1+++, NA+, BA++,CU++, CU+, MG++, GA+++, IN+++, T1+++,SN++++, LI+, ZN++, AG+, NI++, CO++, AND MN++; WHEREIN A IS AN ANIONSELECTED FROM THE GROUP CONSISTING OF I-,BR-,NO3-,SO4--, AND SCN-, ANDWHEREIN X AND Y ARE INTEGERS SUCH THAT THE TOTAL CHARGE ON THE CATIONPROTION OF THE MOLECULE EQUALS THE TOTAL CHARGE ON THE ANION PORTION OFTHE MOLECULE, FORMING THE SOLUTION INTO THE FORM OF FILAMENTS, REMOVINGFROM THE FORMED FILAMENTS SUBSTANTIALLY ALL THE SOLVENT COMPOSITIONPRESENT THEREIN, AND DRAFTING THE RESULTING FILAMENTS WHEREBY THERE AREPROVIDED FILAMENTS SUITABLE FOR USE IN THE MANUFACTURE OF TEXTILES. 12.THE METHOD OF CLAIM 10 WHEREIN THE FILAMENTS ARE FORMED BY EXTRUDING THESPINNING SOLUTION INTO AN ATMOSPHERE OF AIR MAINTAINED AT A TEMPERATUREOF FROM ABOUT 140* C. TO 200* C. TO REMOVE THEREFROM SUBSTANTIALLY ALLSOLVENT.